1. Field of the Invention
This invention concerns an improvement of the soft soil stratum and, more specifically, relates to soil stabilization by supplying cement or other powdery stabilizing agent into the ground by jet injection method and mixing and agitating the same with the soil for chemical solidification in-situ.
2. Description of the Prior Art
As is well-known, soil stabilization for the soft soil stratum has generally been performed by the injection of chemical grouting. However, injection of chemical grouting has drawbacks in that the chemicals contaminate underground water so as to bring about public pollution, control for the chemical reaction is difficult, and the choice of the chemicals is restricted.
In view of the above, new soil stabilization by supplying a powdery stabilizing agent such as cement, quick lime or slug into the soft ground, mixing and agitating the same with the underground soil for solidification in-situ chemically has recently been developed.
However, in the case where the powdery stabilizing agent has to be introduced deep within the ground, a difficulty in transporting the powdery stabilizing agent from above the ground to the intended underground level may arise. There has been developed a technique involving supplying the powdery stabilizing agent under pressure through a transportation channel pipe disposed along the outer surface of a rotary shaft. However, if the powdery stabilizing agent is transported to an extremely great depth, clogging may be caused by the powdery stabilizing agent in the transportation channel pipe failing to obtain a sufficient power supply under pressure. Furthermore, it is impossible to measure and control the amount of the powdery stabilizing agent jetted into the soft soil stratum thus making it difficult to perform satisfactory soil stabilization.